Research

Overview

Prof. Lee’s research group, which is also known as “Nano Energy and Interface Lab” is interested in light energy conversion application, in particular, solar cells and photocatalytic system. Brief descriptions for the research topics are explained below,

I. Development of earth abundant, nontoxic, and efficient light absorber materials

The light absorber is an essential part not only to decide the range of absorption spectrum and the number of photons available for light energy harvest but also to determine the number of carriers injected through an interface relating to their material, optical, and electrical properties. various conventional materials such as CdTe and CdS have been considered an efficient light absorber owing to its excellent optical and electrical properties but we can not avoid of environmental issue with the toxicity of Cd. For the reasons, the materials without the toxicity such as metal oxide and chalcogenide absorbers such as SnS and CuO can be considered as promising alternatives due to their abundancy, nontoxicity, and excellent optical properties. In addition, modifications of the materials such as doping or surface treatment would provide their unique features and/or improve the performance of solar energy conversion. Therefore, we develop and investigate these promising materials for solar energy conversion system.

II. Fabrication and application of nanostructured materials to solar energy applications

Materials exhibit unique features when prepared in nanoscale. For instance, nanostructured semiconductor exhibits extended carrier lifetime, directed carrier transport, or different distribution of density of states. Nanostructured metals, in particular, made of novel metals such as Au, or Ag possess excellent light absorption activated by plasmonic effect. The incorporation of these features to the solar energy application would be beneficial for the enhancement of their performance. We study on the fabrication and characterization of various nanostructured materials fabricated by chemical and physical methods.

III. Design and study on effective interfaces for solar energy conversion: For enhanced performance of solar energy conversion, photo-reactive applications adopt a junction structure. For instance, various type of junctions such as hetero- or homojunction, Schottky junction, pn junction, or ohmic junction play an essential role in the operation of the solar conversion applications. In addition, the properties of interfaces made by these junctions are also determinant of the performance. These various junctions and the properties of interfaces govern charge behaviors affecting important parameters of the materials such as carrier lifetime or carrier mobility, through bulk materials and interfaces. Hence, our focus on these topics is understanding interface properties and engineering carrier behaviors through solar energy conversion system.